Near field communication overview

Near Field Communication (NFC) is a set of short-range wireless technologies, typically
requiring a distance of 4cm or less to initiate a connection. NFC allows you to share small
payloads of data between an NFC tag and an Android-powered device, or between two Android-powered
devices.

Tags can range in complexity. Simple tags offer just read and write semantics, sometimes with
one-time-programmable areas to make the card read-only. More complex tags offer math operations,
and have cryptographic hardware to authenticate access to a sector. The most sophisticated tags
contain operating environments, allowing complex interactions with code executing on the tag.
The data stored in the tag can also be written in a variety of formats, but many of the Android
framework APIs are based around a NFC Forum standard
called NDEF (NFC Data Exchange Format).

Android-powered devices with NFC simultaneously support three main modes of operation:

This document describes how Android handles discovered NFC tags and how it notifies
applications of data that is relevant to the application. It also goes over how to work with the
NDEF data in your applications and gives an overview of the framework APIs that support the basic
NFC feature set of Android.

This document goes over the APIs that enable use of the various tag technologies that
Android supports. When you are not working with NDEF data, or when you are working with NDEF
data that Android cannot fully understand, you have to manually read or write to the tag in raw
bytes using your own protocol stack. In these cases, Android provides support to detect
certain tag technologies and to open communication with the tag using your own protocol
stack.